Synchronous Couplers Made of Symmetric and Asymmetric Slabs
Punya P. Paltani and S. Medhekar
We present a detailed study of TE modes propagation in directional couplers made of symmetric and asymmetric slab waveguides. Three distinct cases are analyzed in our study; first is of a symmetric synchronous coupler second is of an asymmetric synchronous coupler and third is of an asymmetric nonsynchronous coupler. By giving one example for each case, we have provided basic understanding of power switching behavior of these couplers. In the last part of the paper, we have given one simple approximate method to find out the propagation constant of individual slabguides of the compound structure. This method is useful in determining parameters like refractive indices, slab widths of the coupler structure for a synchronous coupler if some parameters are fixed. We have included 3-D grayscale and grid plots to provide physically intuitive visuals of power exchange between the two slab waveguides. The discussion presented in the paper is helpful for beginners as well as for scientists and engineers.